1. Field of the Invention
This invention relates to a process for improving the ultraviolet light transmittance of ethylene glycol by treating industrial grade ethylene glycol with an aluminum-nickel alloy.
2. Description of the Prior Art
There are many methods known for producing ethylene glycol. A commonly used method involves the hydration of ethylene oxide at increased temperatures under pressure. The resulting ethylene glycol produced by this method and other methods known in the art contains many impurities and can be designated as industrial grade ethylene glycol. It may be used in antifreeze or other products where highest purity is not required.
The so-called industrial grade ethylene glycol must be distinguished from fiber grade ethylene glycol which is used to make polyesters and other synthetic fibers. Among other requirements, fiber grade must not contain significant amounts of impurities which will result in the low transmittance of ultraviolet light. In order to be acceptable as fiber grade ethylene glycol, the ethylene glycol generally must have an ultraviolet transmittance of at least 70 percent at 220 nanometers, at least 90 percent at 275 nanometers, and at least 95 percent at 350 nanometers.